Ortho-hydroxy-carboxylic acids of fluorene



Patented July 12, 1932 UNITED STATES PATENT OFFI FRITZ BALLAUF AND ALBERT scriMELzna, OF ELBERFELD, GERMANY, AssIGNoRs To. I. G. FARBENINDUSTEIE AKTIENGESELLSCHAFT, 0F FRANKFORT-ON-THE-MAIN,..

GERMANY, A CORPORATION OF GERMANY ORTHO-HYDROXY-GARBOXYLIC ACIDS OF FLUORENE No Drawing. Application filed January 17, 1930, Serial No. 421,589, and in" Germany .Ilamiary 23, 119F935 The present invention relates to a process of preparing ortho-hydroxy-carboxylic acids of fluorene and to the new compounds obtainable thereby, more particularly it relates to compounds of the general formula:

1 2 H CHA wherein one 1r stands for hydrogen and the other 0: stands for a carboxylic acid group.

Our new compounds are obtainable by causing carbon-dioxide to act on Q-hydroxyfluorene at elevated temperature and superatmospheric pressure in the presence of an alkali-hydroxide, -bicarbonate or carbonate. The temperature and the pressure used may be varied in the widest limits, temperatures between about 250 G. and superatmospheric pressures quite generally having been found to be suitable; preferably, the process is carried out at temperatures between about 150200 G. and a carbon-dioxide pressure of between about 540 atmospheres The quantity of the alkali to be added to the hydro-xyfiuorene may range within wide limits, but in order to complete the reaction at least an equivalent quantity must be present, that is, a quantity sufficient for the formation of the alkali metal salt of the hydroxy-fluorene; thus, when working with alkali metal hydroxides and bicarbonates, molecular quantities are used, while, when working with alkali metal carbonates, half of a' molecular quantity is used. During the reaction the pressure continuously decreases, and the process is complete when the pressure does not change any more, say after about 20 hours, the time required depending on the specific temperatures and pressures used.

Instead of starting with a mixture of 2- hydroxy-fluorene and an alkali metal-hydroxide, -carbonate or -bicarbonate, there may be used an alkali metal salt of 2-hydroxy-fiuorene, which process is equivalent to that heretofore described.

The new fluorene-ortho-hydroxy-carboxylic acids are. yellowish or greyish substances, the 2-hydroxy-fluorene-3-carboxylic acid being scarcely soluble in alcohol and having a melting point of 256260 0., the 2'-hydroxyfluorene-l-carboxylic acid being easily soluble in alcohol and having a melting point of 235240 C. They are valuable intermediate substances for the manufacture of dyestuffs and therapeutical agents.

The invention is illustrated by the following examples, without being limitedthereto:

Example 1.- parts by weight of Q-hydroxy-fluorene are finely ground with 350 parts by weight of potassium bicarbonate andylic acid which issoluble with difficulty in alcohol, being a. yellowish substancemel'ting at 256260 C. with decomposition, and 40 per cent of 2-hydroxy fluorene-1rcarboxylic acid easily soluble in alcohol. It is, a greyi-sh 1 product melting at 236-240" C. with decomposition. They give the blue iron chloride reaction typical of the ortho-hydroxy acids. Example 2.--20.4L parts. by weight of the sodium salt of2-hydroxy-fluorene are introduced into an autoclave with the addition of glass beads. Carbon-dioxide is then forced in, and the mixture is maintained at C. and 35 atmospheres for about 24 hours. After cooling, the reaction mass is worked up as described in Example 1, about 60 per centof 2-hydroxy-3-carboxylic acid and 40 per cent of 2-hydroxy-fluorene-l oarboxylic acid bein obtaine V wample 51-415 parts by weight of 2-hydroxy-fluorene are finely ground with 200 of glass beads.

troduced into an autoclave with the addition Carbon-dioxide is then forced in, and the mixture is maintained at 200 C. and under a pressure of 30 atmospheres for about 20 hours. Theworking up of the reaction mixture is efiected as described in Example 1. Yield about 65 per cent of 2-hydroxy-flu0rene-g-carboxylic acid and 35 g per ce'nt of 2-hydroxy-fluorene-l-carboxylic acid.

We claim:

, 1. The processlwhich comprises causing v v carbon-dioxide to react upon 2-hydroxy-' fluorene at a temperature between about -200 C. and at a pressureiof 540 atmo si pheres-in the presence of an alkali metal compound of the group consisting of hydroxide, carbonates and bicarbonates.

2.. The process which comprises causing carbon-dioxide. to react upon 2-hydroxyfluorene' at a temperature between about 150200 "C.fand at a pressure of 5-40 atmospheres in the presence of an at least equivalent quantity of an alkali metal compound a of the group consisting of hydroxides, carbonates and bicarbonates.

3. The process which comprises causing carbon-dioxide to react upon 2hydroxyfiuorene at a'temperature of C. and at a pressure of 40 atmospheres in the presence of an at least molecular quantity of potassium bicarbonate.

4. As new products compounds of the probable general formula:

wherein one as stands for hydrogen and the other '00 stands for a carboxylic acid group, the

2-hydroxy-fluorene-3-carb0xylic acid being a yellowish substance, scarcely soluble in alcohol and melting at 256-260 0., the 2-hydroxy-fluorene-1-carboxylic acid being a greyish-white colored substance, easily soluble in alcohol, melting at 236240 (3., being valuable intermediate products for the manufacture of dyestufils and pharmaceutical agents. 1

In testimony whereof, we afiix our signatures.

' FRITZ'BALLAUF.

ALBERT SCHME LZER. 

